For the Consumer

In addition to its needed effects, some unwanted effects may be caused by methotrexate (the active ingredient contained in Folex PFS). In the event that any of these side effects do occur, they may require medical attention.

Major Side Effects

You should check with your doctor immediately if any of these side effects occur when taking methotrexate:

More common:

Black, tarry stools

blood in the urine or stools

bloody vomit

diarrhea

joint pain

reddening of the skin

sores in the mouth or lips

stomach pain

swelling of the feet or lower legs

Less common:

Back pain

blurred vision

confusion

convulsions (seizures)

cough or hoarseness

dark urine

dizziness

drowsiness

fever or chills

headache

lower back or side pain

painful or difficult urination

pinpoint red spots on the skin

shortness of breath

unusual bleeding or bruising

unusual tiredness or weakness

yellow eyes or skin

Minor Side Effects

Some of the side effects that can occur with methotrexate may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

Gastrointestinal

Very common (10% or more): Anorexia, nausea, vomiting, abdominal pain, inflammation, ulcerations of the mucous membrane of mouth and throat (especially during the first 24 to 48 hours after administration), stomatitis, dyspepsia, dehydrationCommon (1% to 10%): Diarrhea (especially during the first 24 to 48 hours after administration)Uncommon (0.1% to 1%): GI bleeding and ulcers, pancreatitisRare (0.01% to 0.1%): Gingivitis, enteritis, melena, malabsorption Very rare (less than 0.01%): Hematemesis, toxic megacolonFrequency not reported: Glossitis[Ref]

General

Generally, the incidence and severity of acute side effects are related to dose and frequency of administration. The most frequently reported adverse reactions include ulcerative stomatitis, leukopenia, nausea, abdominal distress, malaise, undue fatigue, chills and fever, dizziness, and decreased resistance to infection.[Ref]

Preexisting myelosuppression or low hematologic cell counts are contraindications to the use of this drug, particularly in patients with rheumatoid arthritis or psoriasis. Close monitoring of the CBC is mandatory. Profound count nadirs may require therapy discontinuation, at least temporarily. Folate therapy and/or leucovorin rescue may be preventive or palliative. Treated patients who become febrile should be assumed to have neutropenia until proven otherwise.

Cytopenia occurs in 5% to 25% of patients with rheumatoid arthritis (RA) who receive long-term therapy. Risk factors include renal dysfunction, preexisting folate deficiency, increased mean corpuscular volume value, advanced age, concomitant use of other anti-folate medications (such as trimethoprim-sulfamethoxazole), and possibly hypoalbuminemia, concomitant infection, history of bone marrow injury, surgery, and concurrent use of NSAIDs or probenecid. Pancytopenia is rarely observed in patients with rheumatoid arthritis. Bone marrow recovery typically occurs within two weeks after the withdrawal of MTX.[Ref]

Methotrexate can cause acute elevations of liver function tests (elevated serum transaminases in 15% of patients with rheumatoid arthritis (RA) on low-dose therapy) or chronic hepatotoxicity (fibrosis and cirrhosis). The incidence of liver fibrosis and cirrhosis in patients with RA (low doses) averages 3% to 7% and 0.1%, respectively. Meta-analysis has revealed the incidence of progression of liver disease (worsening of 1 grade on the histologic classification of Roenigk) in patients with RA or psoriatic arthritis averages 27%, or 7% per gram of MTX (total dose) given. Chronic hepatotoxicity typically develops only after chronic use of higher doses (2 years or more of total doses of 1.5 grams or more), is more likely in patients who ingest ethanol, who are aged, who are obese, who have chronic renal insufficiency, or who have diabetes.

In general, the following serve as guidelines for patients with non-oncologic conditions:

1) Screen all patients to be treated with complete liver blood tests (transaminases, albumin, alkaline phosphatase, bilirubin), hepatitis B and C serologic studies (some experts recommend viral serology's only in patients with abnormal liver function tests), baseline serum creatinine and complete blood count (CBC);2) Baseline liver biopsy if the patient has preexisting liver disease, persistently abnormal baseline AST (aspartate aminotransferase), history of excessive alcohol consumption (greater than 3 drinks/day), or chronic hepatitis B or C infection;3) Monitor hepatic enzymes every 4 to 8 weeks (with the understanding that they are not necessarily predictive of fibrosis/cirrhosis), discontinuing MTX if serum transaminase levels meet or exceed 2 to 3x baseline (some guidelines recommend withholding MTX for 1 to 2 weeks if significant abnormalities persist);4) Liver biopsy should be considered if significant hepatic enzyme abnormalities persist for 2 to 3 months. Liver biopsy should be performed if 6 of 12 monthly AST levels are above the upper limit of normal or serum albumin levels are less than normal in the setting of well controlled disease;5) If liver biopsy shows Roenigk grade I, II, or IIIA (mild fibrosis), MTX may be resumed with monitoring as described above; if liver biopsy show Roenigk grade IIIB (moderate fibrosis) or IV (cirrhosis), MTX should be discontinued;6) MTX should be discontinued in patients with significant liver abnormalities, as described above, who refuse liver biopsy;7) It is still debated whether post-therapy biopsy should be performed every 2 to 3 years or after each 1.5 to 2.0 grams cumulative dose given, regardless of liver chemistries.

*Pre-biopsy coagulation studies and withholding of aspirin and other NSAIDs are recommended.[Ref]

New and/or opportunistic infection can arise during or after therapy with methotrexate due to drug-induced immune suppression. Infections during MTX therapy may occur in up to 58% of patients during low-dose therapy (as in RA). Patients are at great risk after high-dose therapy.

MTX should be held prior to and during elective surgery to minimize the risk of infectious complications.

Limited data have shown that the use of low-dose MTX for patients with rheumatoid arthritis is associated with decreased CD8 and naive CD4 T lymphocytes after only 8 weeks of therapy.

Methotrexate is usually contraindicated in patients with overt or laboratory evidence of immunodeficiency syndromes. Immunization may be ineffective when given during methotrexate therapy. Immunization with live virus vaccines is generally not recommended. There have been reports of disseminated vaccinia infections after smallpox immunization in patients receiving methotrexate therapy.[Ref]

Professional resources

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